Mags should be locked in your pistol case or suitcase UNLOADED. According to TSA rules you can put loaded mags into your luggage if the open ends are covered as inserted into a belt mag holder, but I have seen airline reps who wouldn't allow it, so to be safe, travel with mags unloaded to guarantee a hassle free trip.

Ammo can be placed in your checked bag no problem. Conform with ammo box rules and the airline's rules and you'll be fine.

Again, my .02

Couldn't have said it any better, other than the one edit. Some airlines get sticky with ammo in checked bags. But in general there's no problem.

__________________ôSay what you will about the sweet miracle of unquestioning faith, but I consider the capacity for it terrifying...--Kurt Vonnegut